Corrosion behavior of a ZrCN coated Ti alloy with potential application as a bipolar plate for proton exchange membrane fuel cell

Abstract

a b s t r a c tTo improve the corrosion resistance, surface electrical conductivity and wettability of Tie6Ale4V used in polymer electrolyte membrane fuel cell (PEMFC), a ZrCN nanocrystalline coating was deposited on Ti e6Ale4V substrate using double cathode glow discharge technique. The new coating exhibited a nanocomposite structure, consisting of amorphous C, CN x and nanocrystalline ZrCN. The effect of the HF concentrations on the corrosion behavior of the coating was investigated by potentiodynamic, potentiostatic polarizations and electrochemical impedance spectroscopy (EIS) in a simulated the operating conditions of a PEMFC. With increasing HF concentrations, the corrosion potential (E corr ) decreased and the corrosion current density (i corr ) of the ZrCN coating increased, indicating that corrosion resistance decreased with the increase of HF concentrations. However, at any given concentration of HF, the corrosion resistance of the ZrCN coating was significantly higher than that of uncoated Tie6Ale4V. The results of EIS measurements showed that with increasing the concentration of HF, the resistance of the passive film (R b ) formed on the ZrCN coating decreased slightly, being of the order of magnitude of 10 7 U cm 2 , which was an improvement by four orders of magnitude compared to uncoated Ti-6A1-4V. At a compaction force of 140 N cm À2 , no perceptible difference in the interfacial contact resistance (ICR)of ZrCN-coated Ti-6A1-4V was observed before and after potentiostatic polarization for 120 min, and its ICR values were reduced by one order of magnitude in comparison to that of uncoated Ti-6A1-4V. Moreover, ZrCN-coated Ti-6A1-4V exhibited a much low surface wettability than uncoated Tie6Ale4V alloy, which was beneficial for both water management and improving corrosion resistance.

Corrosion Behavior and Conductivity of TiNb and TiNbN Coated Steel for Metallic Bipolar Plates

“…The angles are shifted to lower values indicating some stress. For the TiNbN coating, the Bragg angles of diffraction peaks are between those of TiN and NbN, which denotes that TiN and NbN are likewise a solid solution [26]. Moreover, diffraction peaks arising from (111), (200), (220), (311), and (222) plane reflections are clearly identified, confirming the face centered cubic (fcc) crystalline structure.…”

Electrochemical Properties of Niobium Modified AISI316L Stainless Steel Bipolar Plates for Direct Formic Acid Fuel Cell

“…When n = 1, Z CPE presents an ideal capacitance. On the contrary, when n = 1, it is equal to a pure resistor impedance , . In point of fact, n is in the range between 0 and 1, and thus Q could be approximated as a capacitor , .…”

“…In the anode side of DFAFC stacks, the bipolar plates have to face additional higher concentration of formic acid besides the inevitable corrosion environment of PEMFCs , . The formic acid contained in the DFAFC increases the electrochemical corrosion of bipolar plates, shortening their service life , , . The corrosion products on the surface would increase the interfacial contact resistance and poison the catalyst, thus decreasing the power output of the fuel cells .…”

Challenges and Perspectives of Metal‐Based Proton Exchange Membrane's Bipolar Plates: Exploring Durability and Longevity

“…Xu et al. elaborated on work they conducted on zirconium (Zr)‐based ceramics . A thick ZrC (15 μm) and a thick ZrCN (16 μm) coatings were applied on Ti6Al4V alloy, showing a significant change between the electrochemical behaviors of coated and uncoated alloys.…”

“…a) Potentiodynamic polarizations; b) ICR measurements of ZrCN‐coated and bare Ti‐6Al‐4V alloy. Reproduced with permission . Copyright 2016, Elsevier.…”